| Recently the Fe3O4magnetic nanoparticles (FMPs) which has properties of nano materialsand the special magnetic properties was widely used in environmental treatment, chemicalsynthesis and medical domain. In this paper, firstly the characteristic, kinds and normalsynthetic methods of magnetic nanoparticles was summarized. And then the synthetic methodsof the core-shell magnetic nanoparticles and applications in adsorption and detection of heavymetal was described in detail. At last the Fe3O4based material was used in the adsorption anddetection of heavy metal. The main contents of this paper include: the synthesis andcharacterization of various materials, the adsorption behavior of heavy material ions on themagnetic nanoparticles with different disaggregation models and the establishment of magneticnanoparticles assisted atomic fluorescence spectroscopy(AFS) for detecting of trace Hg2+insolution. The conditions of adsorption experiment and instrument parameters were optimized.The realwater samples were analyzed.The details are listed as following:Firstly, the adsorption behaviour of Cr (VI) on FMPs in different disaggregation modelswas studied. The results show that the adsorption capacity of FMPs to Cr (VI) was6times byusing ultrasonic rather than the mechanical agitation. Further study showed that the adsorptioncapacity of FMPs increased233%and310%respectively with the increasing of ultrasonicfrequency from40kHz to59kHz and the ultrasonic power from50W to200W. The adsorptionisotherm and kinetics fitted the Langmuir isotherm model and pseudo-second-order model well.The characteristic of FMPs was studied by scanning electron microscope (SEM), EnergyDispersive Spectrometer (EDS) and Fourier Transform Infrared Spectroscopy (FTIR), it couldbe easily observed that the structure of FMPs was not changed by ultrasonic. The photographand experiment data shows that the ultrasonic can effectively prevent the aggregation of FMPsand then improve the dispersibility of material. Therefore, we speculate that the ultrasonic canimprove not only the dispersibility of FMPs, but also increase the number of active sites onadsorbent. Thus the adsorption capacityofFMPs was promoted signaly.Secondly, new FMPs based AFS system for detecting ultratrace heavy metal ions by usingthe Au nanoparticles deposited FMPs (Au-FMPs) was put forward. The experiment resultshowed that the ng L-1level of Hg2+can be enriched in very short time by Au-FMPs,furthermore the material can be easily separated by external magnetic field and recycling aftersimple treatment. It can be clearly observed that the size ofAu nanoparticles deposited on FMPswas about10nm through the transmission electron microscope (TEM) photograph. The X-rayPowder Diffraction (XRD) spectrum shows that FMPs was partly oxidated during the processof material preparation. Under the optimized conditions, the detection limit (3σ) ofI-Hg was0.6ng L-1, the linearity range was between20-600ng L-1, and the relative standard deviation (RSD) was2.7%. This system has been applied satisfactorily to the determination of trace Hg2+innature water sample, and the recoverywas96.2-104.6%.Finally, Fe3O4@GO (oxidized graphene), Fe3O4@C and Au-Fe3O4were synthesizedrespectively, and the adsorption capacity was also studied. It was found that the adsorptioncapacity of Au-Fe3O4was higher than Fe3O4@C and Fe3O4@GO. But Fe3O4@C andFe3O4@GO had a better water solubility. The prepared composite were characterized by SEM,EDS and FTIR. Furthermore, factors of adsorption on Au-Fe3O4such as kinds andconcentration of media, the mass of adsorbent and the concentration of Hg2+were optimized.The adsorption kinetics and thermodynamic data was also calculated. |
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